中国的空气污染：连续5天黄色警报

A third-level yellow smog alert has been issued for a fifth straight day. Environmental authorities say 15 percent of the country is experiencing smog.

Particularly dense smog is concentrated in north, east and central China. In Dalian city of Liaoning province, 78 flights were cancelled on Sunday. Visibility was less than 50 meters. The airport arranged hotel accommodations for more than 3,000 stranded passengers. Shijiazhuang, capital of Hebei Province, went on orange alert, the second highest, early Sunday morning. The air quality is not expected to improve until Thursday.